In a fully charged state of the battery is indeed temporarily 3-4 hours time remaining, but that settles down soon to 2 hours a. Pass inaccuracies I could not tell. An original battery was a bit too expensive. - Bought in June 2010. 15 months later still ok. Since yesterday I have also got our second (same) MacBook Pro 15 "Mid / Late 2007 (A1226) to the same battery. Fits again exactly, let's see if he's so good. In June 2013 he still holds 2 1 / 2 hrs.